In diagnosing and treating certain medical conditions, it is often desirable to perform a biopsy, in which a specimen or sample of tissue is removed for pathological examination, tests and analysis. A biopsy typically results in a biopsy cavity occupying the space formerly occupied by the tissue that was removed. As is known, obtaining a tissue sample by biopsy and the subsequent examination are typically employed in the diagnosis of cancers and other malignant tumors, or to confirm that a suspected lesion or tumor is not malignant. Treatment of cancers identified by biopsy may include subsequent removal of tissue surrounding the biopsy site, leaving an enlarged cavity in the patient's body. Cancerous tissue is often treated by application of radiation, by chemotherapy, or by thermal treatment (e.g., local heating, cryogenic therapy, and other treatments to heat, cool, or freeze tissue).
Cancer treatment may be directed to a natural cavity, or to a cavity in a patient's body from which tissue has been removed, typically following removal of cancerous tissue during a biopsy or surgical procedure. For example, U.S. Pat. No. 5,429,582 to Williams, U.S. Pat. No. 5,913,813 to Williams et al., U.S. Pat. No. 5,931,774 to Williams et al., U.S. Pat. No. 6,022,308 to Williams, U.S. Pat. No. 6,083,148 to Williams, and U.S. Pat. No. 6,413,204 to Winkler et al., the disclosures of which are all hereby incorporated by reference in their entireties, describe devices for implantation into a cavity resulting from the removal of cancerous tissue which can be used to deliver cancer treatments to surrounding tissue. One form of radiation treatment used to treat cancer near a body cavity remaining following removal of tissue is “brachytherapy” in which a source of radiation is placed near to the site to be treated.
Williams and coworkers describe implantable devices for treating tissue surrounding a cavity left by surgical removal of cancerous or other tissue that includes an inflatable balloon constructed for placement in the body cavity. Such devices may be used to apply one or more of radiation therapy, chemotherapy, and thermal therapy to the tissue surrounding the body cavity from which the tissue was removed. The balloon may be filled with a treatment fluid delivered via a conduit from a receptacle, syringe, or other means, or may receive a solid radiation source placed within the balloon. Thus, radiation treatment may be applied to tissue adjacent the balloon by placing radioactive material such as radioactive “seeds” within the balloon, or by filling the balloon with a liquid or slurry containing radioactive material. Multiple treatments may be applied simultaneously. For example, radioactive seeds may be placed within the balloon effective to irradiate tissue surrounding the balloon, and the balloon filled with a hot fluid at the same time to provide thermal treatment. After a suitable time, the hot fluid and/or the radioactive seeds may be removed. Such treatments, combined or otherwise, may be repeated if desired.
For example, a “MammoSite® Radiation Therapy System” (MammoSite® RTS, Proxima Therapeutics, Inc., Alpharetta, Ga. 30005 USA) includes a balloon catheter with a radiation source that can be placed within a tumor resection cavity in a breast after a lumpectomy. It can deliver a prescribed dose of radiation from inside the tumor resection cavity to the tissue surrounding the original tumor. The radiation source is typically a solid radiation source; however, a liquid radiation source may also be used with a balloon catheter placed within a body cavity (e.g., Iotrex®, Proxima Therapeutics, Inc.). The radiation source may be removed following each treatment session, or may remain in place as long as the balloon remains within the body cavity. Inflatable treatment delivery devices and systems, such as the MammoSite® RTS and similar devices and systems (e.g., GliaSite® RTS (Proxima Therapeutics, Inc.)), are useful to treat cancer in tissue adjacent a body cavity.
However, radiation, chemotherapy, thermal treatment, and other cancer treatments often have deleterious effects on healthy tissue in addition to the desired effects on cancerous tissue. In such treatments, care must be taken to direct the maximum treatment effects to diseased tissue while minimizing its delivery or effects on healthy tissue. For example, radiation treatment may be most effective when all surrounding tissue regions receive the same dose of radiation, and where the radiation dosage received by more distant tissue is as small and as uniform as possible. However, tissue cavities typically are not uniform or regular in their sizes and shapes, so that differences in dosages applied to different regions of surrounding tissue, including “hot spots” and regions of relatively low dosage, often result from radiation treatment.
Thus, there is need in the art for improved devices and methods for delivering cancer treatment to a cavity site within a patient's body.